The present invention relates to a mechanical seal device which, between a processing equipment where to perform processing under a sterile condition and a rotary shaft used with one end thereof inserted in the processing equipment, seals the rotary shaft and is provided between the processing equipment and the atmosphere, and to provide a processing apparatus.
As a known processing apparatus for agitating, as shown in FIG. 9 for example, a treatment solution or the like, known is an apparatus in which the treatment solution is stored in a processing equipment 100, a rotary shaft 101 provided with, for example, an impeller at its one end is inserted in the processing equipment 100 from an atmosphere side, and the rotary shaft 101 is rotated around its axis by a motor or the like connected to the other side of the rotary shaft 101 to agitate the treatment solution. The aforesaid agitation process is sometimes performed while unwanted bacteria are prevented from getting mixed in the treatment solution, as in, for example, the preparation of an injection solution, or chemical processes such as cell incubation and crystallization for obtaining sterile powder. In performing such a process in the aforesaid apparatus, the inside of the processing equipment 100, the rotary shaft 101 (impeller), and so on are sterilized with sterilizing gas such as, for example, saturated steam, for example, before the treatment solution is charged into the processing equipment 100, or before the process is started after the treatment solution is charged into the processing equipment 100. For this sterilization, for example, the saturated steam at 100° C. or higher is sufficiently supplied in order to surely sterilize the apparatus.
A known method used in the aforesaid apparatus to seal the rotary shaft 101 relative to the processing equipment 100 and airtightly seal a gap between an inner area of the processing equipment 100 and the air atmosphere is, for example, a method using a mechanical seal 101 or the like as described in Patent Documents 1, 2. This mechanical seal 102 includes seal members 103, 104 on the processing equipment 100 side and the rotary shaft 101 side respectively, having seal surfaces that seal on each other along a circumferential direction of the rotary shaft 101, and seals the rotary shaft 101 which rotates around its axis relative to the processing equipment 101, by making these seal surfaces seal on each other. In FIG. 9, 105 denotes a housing (casing) housing these seal members 103, 104.
Further, for the purpose of airtightly sealing the gap between the inside of the processing equipment 110 and the air atmosphere, preventing the friction between the seal members 103, 104, and letting out heat generated by the sliding, a sealing fluid, for example, a sealing gas or the like is supplied to a seal part 110 which is an area between the seal surfaces of these seal members 103, 104. At this time, a pressure in an area supplied with the sealing gas is sometimes set higher than an inner pressure of the processing equipment 100 in order to prevent the treatment solution or the like from leaking out from the processing equipment 100 via the seal part 110. Concretely, the seal members 103, 104 are disposed so that the aforesaid seal part 110 is formed at, for example, two places along a length direction of the rotary shaft 101 to form a double mechanical seal, and from a sealing fluid supply path 107, the sealing gas having a higher pressure than the inner pressure of the processing equipment 100 is supplied to a sealing fluid supplied area 106, which is an airtight area in a ring shape formed at a position that is between these seal parts 110 and between the rotary shaft 101 and the casing 105. Therefore, the sealing gas supplied to the sealing fluid supplied area 106 slightly enters the inside of the processing equipment 100 via the seal part 110 on the processing equipment 100 side and leaks out to the atmosphere side via the atmosphere-side seal part 110.
Therefore, in a process that is performed while unwanted bacteria are prevented from entering the processing equipment 100 as described above, clean gas is also used as the sealing gas. Further, in order to prevent unwanted bacteria from entering the processing equipment 100 via inner wall surfaces of areas where the sealing gas flows (the sealing fluid supplied area 106 and the sealing fluid supply path 107), these areas are also sterilized by the supply of the aforesaid saturated steam from the sealing fluid supply path 107 to the sealing fluid supplied area 106 at the time of the sterilization of the processing equipment 100 and the rotary shaft 101. Accordingly, the seal part 110 on the processing equipment 100 side out of the aforesaid two seal parts 110 is supplied with the saturated steam both from an inner peripheral side (the processing equipment 100 side) and an outer peripheral side (the sealing fluid supplied area 106 side), so that the temperature and pressure of the saturated steam in this seal part 110 are maintained, ensuring the sterilization of the seal part 110 under the same sterilization condition as that in the processing equipment 100.
As for the atmosphere-side seal part 110 (opposite the processing equipment 100), since an atmosphere of an area to which the steam leaks from this seal part 110 is, for example, the air atmosphere, the saturated steam leaking from the sealing fluid supplied area 106 to the air atmosphere gradually decreases in temperature and pressure to be condensed, so that its sterilizing operation weakens. Therefore, it cannot be said that the seal part 110 adjacent to the atmosphere is sterilized on the same level as that for the seal part 110 on the processing equipment 100 side.
However, since the seal part 110 adjacent to the atmosphere communicates with an inner atmosphere of the processing equipment 100 via the sealing fluid supplied area 106 and the seal part 110 on the processing equipment 100 side, the atmosphere-side seal part 110 also needs the sterilization process on the same level as that of the seal part 110 on the processing equipment 100 side in order to surely prevent unwanted bacteria from entering the processing equipment 100. A possible method to sterilize this atmosphere-side seal part 110 on the same level as that for the seal part 110 on the processing equipment 100 side is to set the temperature and pressure of the steam supplied to the sealing fluid supplied area 106 higher than values necessary for the sterilization so that the temperature and pressure necessary for the sterilization are maintained even when, for example, the temperature and pressure decrease due to the leakage of the steam from this seal part 110, but this requires an additional amount of energy for heating the steam, and necessitates imparting high heat resistance to members forming the mechanical seal 102, which leads to a cost increase of the apparatus. Further, providing a heat-insulating cover covering the whole mechanical seal as described in Patent Document 3 requires an extremely high heat energy.
Another known method is to dispose the aforesaid mechanical seal at three places along the length direction of the rotary shaft, but the seal part adjacent to the atmosphere is not sterilized, either, on the same level as that for the seal part 110 on the processing equipment 100 side.